The present invention concerns a bottle top that comprises a tough-plastic outer cap, a tough-plastic inner cap, and a soft polymer stopper. The stopper fits inside the inner cap. The bottle has a bead around its neck. The wall of the inner cap is composed of several vertical strips. The strips are resilient radially outward and are held against the neck of the bottle by the outer cap. The bottom ends of the strips have a beveled-in edge that engages the bottom edge of the bead, forcing the stopper against the upper surface of the bottle's neck. At least one area of the inner cap's roof rips out.
A bottle top of this type is known from German Published Patent Application No. OS 4 015 510. It is intended for transfusion and infusion bottles. It has a cap with a wall composed of vertical radially outwardly resilient strips that engage the bottom edge of a bead around the neck of a bottle. The cap is secured to the neck by a ring of hard plastic thrust over the cap and holding the strips in place. The cap also has locking strips that prevent removal of an outer cap. This bottle top has several drawbacks. The stopper is not forced uniformly enough against the upper surface of the bottle's neck to ensure a tight seal. The top is difficult to assemble. Discrepancies in the thickness of the bead occur that cannot be sufficiently compensated for by the beveled-in edge of the inner cap, allowing leaks from the irregular pressure of the stopper against the upper surface of the neck.
German Utility Model Patent No. GM 8 807 750 describes a plastic top for containers that are at least similar to bottles. An outer cap screws onto the inner cap, which is an integral component. The inner cap engages a bead integrated into the neck of the container. The inner cap rests against the whole circumference of the bead. The bead extends radially outward. The inner cap engages it with a claw that extends essentially radially inward. The inner and outer caps and bottle neck must be manufactured to very precise tolerances to ensure tightness, which leaves much to be desired from the aspect of manufacturing simplicity and cost. An O-ring is positioned against surface of the outer cap that faces the bottle. The O-ring comes apart at weak points when the outer cap is unscrewed from the inner cap.
Other tops are known that have a rubber stopper or disk forced against the neck of a medicine bottle by a metal cap. They are applied in two spatially separated manufacturing steps. First, the stopper is forced against the bottle in a sterile area of the plant. The full bottle is then transferred to another area, where the metal cap is applied and secured with capping machinery. The intention of such a complicated procedure is to keep particles of metal from the cap from contaminating the medicine. Another drawback of metal caps is that the ripped-out sections have dangerously rough edges. They are also complicated to dispose of because most hospitals do not have a separate aluminum-collecting point.